Waste product streams containing primarily water and smaller amounts of nonaqueous liquids and solids, both organic and inorganic, are by-products of processes used in various industries such as the refining, petrochemical and chemical industries, to name a few. For example, a typical waste stream from a refinery operation will contain about 80 percent-by-weight water, about 15 percent-by-weight oil, e.g., hydrocarbons and other nonaqueous liquids, and about 5 percent-by-weight solids. Other processing operations generating similar waste streams include aluminum smelting, and paint, appliance, and automotive manufacturing. Due to environmental regulations, these waste streams pose disposal problems.
It is known to treat a refinery waste stream, commonly referred to as sludge, which is a mixture of solids, water and oil products. Such sludge is treated to obtain either a solids stream that is a slurry of solids, both inorganic and organic, in a primarily aqueous medium, the slurry generally containing from about 15 to about 20 percent-by-weight solids content, or a non-pumpable dry solids cake. Such slurries, containing a relatively small amount, i.e., less than about 10 percent-by-weight, of nonaqueous liquids, e.g., hydrocarbons, can be incinerated. For example, they can be incinerated in furnaces used in spent sulfuric acid regeneration plants, cement kilns or the like. These prior art aqueous slurries have several disadvantages. For one, because of the high water content, they have a low heat value. Additionally, the solids content of the slurries cannot exceed about 20-25 percent lest they become so viscous as to be unpumpable at ambient temperature conditions. Accordingly, the cost of disposing of the slurries is increased because the transportation costs per unit weight of solids is relatively high. In the case of non-pumpable, dry solids cake, the solids content is generally 25 to 90 percent-by-weight. This cake requires special handling for disposal and is considerably more expensive than the slurries to dispose of.
The present invention overcomes the deficiencies of the prior art.